1. Field of the Invention
The present invention relates generally to an armature of a rotating electric machine and, more particularly, to an improvement in production efficiency of an armature of which core is divided into multiple segments along a circumferential direction, the multiple segments being assembled together to complete the core.
2. Description of the Background Art
There exist conventionally known structures of a stator of which laminated core is divided into multiple segments along a circumferential direction of the core, wherein winding density is increased by winding coils on the individual segments of the core to achieve a size reduction and high output power of a rotating electric machine.
One example of such structures is disclosed in Japanese Patent No. 3355700, in which a laminated core is divided into units of magnetic teeth along a circumferential direction and coils are wound around the individual magnetic teeth. The magnetic teeth carrying the coils are assembled into a cylindrical form with projections and recesses alternately formed at circumferential ends of the magnetic teeth fitted together. Then, the magnetic teeth are fixedly joined by welding their fitted ends along a core-laminating direction by using a laser welding machine.
Another example is disclosed in Japanese Laid-open Patent Publication No. 1998-174319, in which a laminated core is also divided into units of magnetic teeth along a circumferential direction and coils are wound around the individual magnetic teeth. In the structure of this Publication, the magnetic teeth carrying the coils are assembled into a cylindrical form with a projection formed at a circumferential end of each magnetic tooth fitted into a recess formed in a facing circumferential end of the adjacent magnetic tooth. An outer extending part of the recess of each magnetic tooth is caulked inward to fixedly join the individual magnetic teeth.
Conventional armatures of rotating electric machines produced by assembling a plurality of separately manufactured magnetic teeth to achieve a high winding density require a process of laser welding or caulking for joining together the individual magnetic teeth as stated above with reference to Japanese Patent No. 3355700 and Japanese Laid-open Patent Publication No. 1998-174319. Since this special and tedious teeth-joining process needs to be performed as many times as the number of the magnetic teeth, the aforementioned conventional structures have been associated with a problem of poor productivity.
The structure of Japanese Patent No. 3355700 requires an expensive laser welding machine for joining the magnetic teeth. In addition, the laser welding machine produces heat which could cause deformation of an armature and a consequent deterioration of properties of a rotating electric machine, such as cogging and torque ripples.
On the other hand, the structure of Japanese Laid-open Patent Publication No. 1998-174319 requires a dedicated caulking machine. The caulking process could also cause deformation of an armature and a consequent deterioration of properties of a rotating electric machine, such as cogging and torque ripples.